Paperclip::Railtie.insert should be wrapped in a initializer block

lib/paperclip/railtie.rb

@@ -4,9 +4,11 @@ module Paperclip
   if defined? Rails::Railtie
     require 'rails'
     class Railtie < Rails::Railtie
+      initializer 'paperclip.insert_into_active_record' do
         ActiveSupport.on_load :active_record do
           Paperclip::Railtie.insert
         end
+      end
       rake_tasks do
         load "tasks/paperclip.rake"
       end